Maria Sharapova has been suspended for two years by the International Tennis Federation for testing positive for meldonium at the Australian Open.

Maria Sharapova was suspended from tennis for two years Wednesday for testing positive for meldonium at the Australian Open, and immediately responded by saying she would appeal the decision to sport’s highest court.

The ruling by an independent three-person panel appointed by the International Tennis Federation said Sharapova did not intend to cheat, but that she bore “sole responsibility” and “very significant fault” for the positive test.

“While the tribunal concluded correctly that I did not intentionally violate the anti-doping rules, I cannot accept an unfairly harsh two-year suspension,” Sharapova said in a statement. “The tribunal, whose members were selected by the ITF, agreed that I did not do anything intentionally wrong, yet they seek to keep me from playing tennis for two years. I will immediately appeal the suspension portion of this ruling to CAS, the Court of Arbitration for Sport.”

The five-time Grand Slam champion was provisionally suspended by the ITF in early March, when she announced at a news conference in Los Angeles that she failed a doping test in January.

“Today with their decision of a two-year suspension, the ITF tribunal unanimously concluded that what I did was not intentional,” Sharapova said. “The tribunal found that I did not seek treatment from my doctor for the purpose of obtaining a performance enhancing substance.

“The ITF spent tremendous amounts of time and resources trying to prove I intentionally violated the anti-doping rules and the tribunal concluded I did not.”

The ban throws into doubt the on-court future of Sharapova, a 29-year-old Russian who is one of the most well-known and — thanks to a wide array of endorsements — highest-earning athletes in the world.

She is a former top-ranked player who is one of 10 women in tennis history with a career Grand Slam — at least one title from each of the sport’s four most important tournaments. So much came so easily for her at the start: Wimbledon champion in 2004 at age 17; No. 1 in the rankings at 18; U.S. Open champion at 19; Australian Open champion at 20.

An operation to her right shoulder in 2008 took her off the tour for months, and her ranking dropped outside the top 100. But she worked her way back, and in 2012, won the French Open, then added a second title in Paris two years later.

Sharapova hasn’t played since a quarterfinal loss to Serena Williams at this year’s Australian Open, and she is ranked 26th this week.

Meldonium increases blood flow, which improves exercise capacity by carrying more oxygen to the muscles.

In April, citing a lack of scientific evidence about how long the drug remains in a person’s system, WADA said that provisional suspensions may be lifted if it is determined that an athlete took meldonium before it went on the list of banned substances.

About 200 athletes tested positive for meldonium this year from various sports and countries — many, like Sharapova, were Russian — and some said the drug stayed in their systems for months even though they stopped using it in 2015.